The present invention relates to a semiconductor component having a cell array that is formed in a semiconductor body and has a number of identical transistor cells and at least one edge cell formed at the edge of the cell array. Each of the transistor cells has a first connection zone of a first conductivity type in the area of a rear face of the semiconductor body, a second connection zone of the first conductivity type in the area of a front face of the semiconductor body, a channel zone of a second conductivity type disposed between the first connection zone and the second connection zone, and at least one control electrode disposed in a trench which extends in the vertical direction into the semiconductor body. The control electrode is insulated from the semiconductor body by an insulation layer, with the trenches of the individual cells disposed at a distance from one another in a horizontal direction of the semiconductor body. The edge cell has a field plate disposed in a trench which extends in the vertical direction into the semiconductor body, and the field plate is insulated from the semiconductor body by an insulation layer.
Components such as these are also referred to as trench transistors.
Fundamental aspects relating to trench transistors are described in U.S. Pat. No. 4,941,026. International Patent Disclosure WO 00/51167, corresponding to U.S. Pat. No. 6,351,018, describes a trench transistor with an integrated Schottky diode, which is formed between two trenches, the distance between which is less than the distance between two trenches of the transistor cells.
A trench transistor with an edge cell is described in U.S. Pat. No. 5,763,915. The known component has a cell array with a large number of transistor cells, which each have a source zone, a body zone, and a gate electrode disposed in a vertical trench. A drain zone that is formed by the substrate of the semiconductor body is shared by the transistor cells. The cell array is bounded in the horizontal direction by an edge cell, which likewise has an electrode disposed in a trench.
It is accordingly an object of the invention to provide a semiconductor component with an increased breakdown voltage in the edge area with a structure for making electrical contact with electrodes of a trench transistor cell that overcomes the above-mentioned disadvantages of the prior art devices of this general type. The aim of the present invention is to provide a semiconductor component having a large number of identically formed transistor cells, which are disposed in a cell array, and has an edge cell, with the breakdown voltage in the area of the edge cell being higher than in the area of the cell array.
With the foregoing and other objects in view there is provided, in accordance with the invention, a semiconductor component. The semiconductor component contains a semiconductor body having a front face, a rear face, and trenches. The trenches are disposed at a distance from one another in a horizontal direction of the semiconductor body and extend in a vertical direction of the semiconductor body. A cell array is formed in the semiconductor body and has an edge area, a number of identically formed transistor cells, and at least one edge cell formed at the edge area of the cell array. Each of the transistor cells has a first connection zone of a first conductivity type disposed in an area of the rear face of the semiconductor body, a second connection zone of the first conductivity type disposed in an area of the front face of the semiconductor body, a channel zone of a second conductivity type disposed between the first connection zone and the second connection zone, at least one control electrode disposed in a respective one of the trenches extending in the vertical direction into the semiconductor body, and a first insulation layer insulating the control electrode from the semiconductor body. The edge cell includes a field plate disposed in another one of the trenches being an edge trench extending in the vertical direction into the semiconductor body, and a second insulation layer insulating the field plate from the semiconductor body. A first distance between the edge trench of the edge cell and the respective trench of an immediately adjacent one of the transistor cells being less than a second distance between the respective trench of the immediately adjacent one of the transistor cells and a further respective trench of a further immediately adjacent one of the transistor cells in the cell array.
The semiconductor component according to the invention has a cell array with a number of identically formed transistor cells, and has at least one edge cell, which is formed at the edge of the cell array, and which are formed in a semiconductor body. Each transistor cell has a first connection zone of a first conductivity type in the area of a front face of the semiconductor body, a second connection zone of a first conductivity type in the area of a rear face of the semiconductor body, a channel zone of a second conductance type disposed between the first connection zone and the second connection zone, and a control electrode disposed adjacent to the channel zone in a trench which extends in the vertical direction into the semiconductor body. The control electrode is insulated from the semiconductor body by an insulation layer. The trenches of the individual cells are disposed at a distance from one another in the horizontal direction of the semiconductor body. The edge cell has a field plate, which is disposed in a trench which extends in the vertical direction into the semiconductor body, and which edge cell is insulated from the semiconductor body by an insulation layer. In order to increase the breakdown voltage in the edge area, provision is made for the distance between the trench of the edge zone and the trench of the immediately adjacent transistor cell to be less than the distance between a trench of a transistor cell and the trench of an immediately adjacent transistor cell in the cell array.
In the case of MOS transistors, the first connection zone is referred to as the drain zone, the second connection zone as the source zone, the channel zone as the body zone and the control electrode as the gate electrode.
The concept according to the invention of making the distance between the trench of the edge cell and the trench of the immediately adjacent transistor cell less than the distance between the rest of the trenches in the cell array, the so-called pitch or pitch interval, is particularly suitable in conjunction with transistor cells in which the control electrodes taper in the vertical direction underneath the channel zone and the thickness of the insulation layer increases in a corresponding manner there. The control electrode is in this case used in the area of the channel zone/body zone as an electrode for forming a conductive channel when a drive potential is applied and, in the lower area, as a field plate for shielding the semiconductor area disposed between two trenches against high field strengths, with this resulting in an increased breakdown voltage in comparison to trench transistors without such field plates.
The transistor cells preferably each have a connection that is in each case disposed between two trenches and extends through the first connection zone into the channel zone. A connection between the trench of the edge cell and the immediately adjacent transistor cell is in one embodiment formed symmetrically between the trenches of the edge cell and of this transistor cell, and in a further embodiment is disposed closer to the trench of the edge cell than to the trench of the transistor cell.
A further embodiment provides for an area to be provided in the cell array in order to produce integrated components that have their connections in the area of the front face of the semiconductor body, in which case the breakdown voltage in this area must not be less than the breakdown voltage of the transistor cells. For this purpose, the distance between two trenches in the cell array on a side that faces away from the respectively associated cell is less than the distance between the trenches of two immediately adjacent transistor cells in the cell array, in order to form a xe2x80x9cprotected areaxe2x80x9d for the integration of low-voltage components between these closely adjacent trenches.
The semiconductor component has a number of transistor cells in a cell array and an area such as this formed in the cell array between two closely adjacent trenches. In which area a semiconductor component is integrated, whose connections are located in the area of the front face of the semiconductor body. The further semiconductor component is, in particular, a bipolar transistor, an MOS transistor or a diode. Multiple wells may be provided in the area between the trenches in order to form the component, with at least one doped well being disposed in another doped well.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a semiconductor component with an increased breakdown voltage in the edge area, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.